Apparatus for making diagonal twisted or skew bends in wave guide tubing



Apnl 3, 1956 F. .1. FUCHS. JR 2,740,454

APPARATUS FOR MAKING DIAGONAL TWISTED OR SKEW BENDS 1N WAVE GUIDE TUBING Filed Oct. 2, 1952 4 Sheets-Sheet 1 2 9: 5 fif V Lil? 5/ 5 if (7 /M%\ \klz INVENTOR 49' iv 1% 49 flazzaa's Jfwig g ATTORNEY April 3, 1956 Filed Oct. 2, 1952 F. J. FUCHS. JR APPARATUS FOR M NG DIAGONAL OR SKEW BENDS TWIS WAVE GUIDE TUBIN 4 Sheets-Sheet 2 INVENTOR ZMM.

ATTORNEY A1311] 3, 1956 FUCHS, JR 2,740,454

APPARATUS FOR MAKING DIAGONAL TWISTED OR SKEW BENDS IN WAVE GUIDE TUBING Filed Oct. 2, 1952 4 Sheets-Sheet 3 zgi 5. /d 5? j} I 5- INVENTOR /j' 6 fiaizzzli rZ/Z'ld) e771,

BY (Ham.

ATTORNEY Apnl 3, 1956 Fuc s, JR 2,740,454

APPARATUS FOR MAKING DIAGONAL TWISTED OR SKEW BENDS IN WAVE GUIDE TUBING Filed Oct. 2, 1952 4 shee -sh 4 INVENTOR A TORNEY United APPARATUS FOR MAKING DKAGQNAL TWISTED R SKEW BENDS IN WAVE SUEDE TUBING Francis 5. Fuchs, Jr., Winston-Salem, N. (3., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application Getober 2, 1952, Serial No. 312,747

12 Ciaims. or. ass-4a;

This invention pertains to the bending of materials, and more particularly to an apparatus for forming diagonal twisted bends in wave guide tubing.

Heretofore several bending operations were necessary to form a twisted and bent wave guide tube, but this is a time consuming and uneconomical process. It is therefore an object of this invention to provide apparatus for forming a diagonal twisted bend in rectangular wave guide tubing in a single bending operation.

A further object of this invention is to form a smooth twisted bend in a wave guide tube so that there will be no folds or wrinkles upon the internal or external surfaces of the finished wave guide tube to impair the transmission qualities thereof.

A still further object of this invention is to provide. an improved pressure die in a bending apparatus.

Another object of this invention is to provide: an. improved forming die for a bending apparatus.

In order to attain these and other objectives, and in accordance with the general features of the invention, one embodiment thereof includes a rotatable forming die having a groove of varying angular cross-section cooperating with a mandrel inserted inside the tubing, a clamping die for securely holding one end of the tubing against the forming die during the bending operation, a pressure die for restraining the other end of the tubing and for permitting the tubing to move rectilinearly along and to rotate around its longitudinal axis, a first pillow block for rotatably supporting the pressure die, a wiping die adjacent the forming die and cooperating therewith to support. the walls of the wave guide tubing during bending. and to allow the wave guide tubing to rotate, and to move rectilinearly along its longitudinal axis, a second pillow block for rotatably supporting the wiping die, a yoke for enclosing said wiping die, said pressure die, and the first and second pillow blocks, and means for. insertingthemandrel into the tubing before the bending operation is initiated.

A. complete understanding of the invention may be obtained from the following detailed description when taken in conjunction with the accompanying drawings wherein:

Fig. l is a plan view of a bending apparatus embodying the. features of the invention;

. Fig. 2 is an end view of the machine shown in Fig; 1 with the tube clamp shown in an exag erated position for clarity;

Fig. 3 is a cross-sectional view taken along line 3--3- of Fig. 1;

Fig. 4 is a cross-sectional view taken along line 4 4 of Fig. 1;

Fig; 5 is a cross-sectional view taken along line 5.--5. of Fig. 4 with the tube clamp in its unoperated position added;

Fig. .6 is a plan view of a second embodiment oflthe 2,74%,454 .Patentecl Apr. 3, 1956 "ice Fig. 7 is a front elevational view of the bending apparatusushown in Fig. 6;

Fig. .8 is a cross-sectional view taken along line 88 of Fig. 6;

Fig. 9 is a cross-sectional view taken along line 99 .of Fig. 6,:

Fig. 1 0 ,is an enlarged fragmentary view of the forming die. shown in Fig. 6;

Fig. 11 is a view similar to that of Fig. 5 but generated in ahorizontal plane and showing the various elements .at the'conclusion, of the bending and twisting operation with the .tube clamp in. its operated position;

Fig. 12 .isa fragmentary perspective view of. a. portion of the pressure die;

Fig. 13 is an enlarged side elevational view of the die shown in Fig. 12 with a shim added, and

,Fig- 14 is a perspective view of a completed wave guide bent by the bending apparatus disclosed in Figs. l-13..

Referring now to the drawings, a base 12 has mounted thereona forming die 13 which is attached to a shaft 14 which is rotated by a sprocket 15 (Fig. 7) driven by a chain drive 16 (Fig. 8). A clamping die 17 is. movable by .a piston into and out of clamping engagement with wave guide tubing 19 (Fig. 2) to be formed to retain the. tubing against the forming die 13 during the bending operation. The clamping die .17 and the piston 20 are connected to the shaft 1dfor rotation therewith by any suitable means, such as by a connecting plate 18. The clamp 17 is slidably connected to the plate 18 by projectingpins 5.6 which slide in slots 57 in the plate when operated by the piston 20 to securely grasp an end 38 of, the wave guide 19,. A bifurcated yoke 21 is attached to the forming die 13 by pins 24 whichextend into circular. guides 25 in the forming die 13. Secured to the yoke 2.1 by pins 58 is a first pillow block 26 (Fig. 3) which has a longitudinal cylindrical sink 27 (Fig. 3)

. therein. A wiper die 29 is nested within the sink 27 and cooperates with the forming die 13 (Fig. 1) tosupport the walls of the wave guide tubing 19 that are in compression during the bending operation. A second pillow block 30 (Fig. 3) is slidable in the yoke 21 and is adjustable by set screws 31. The second pillow block. 30 has therein a longitudinal cylindrical sink 32 wherein a pressure die 34 nests. A mandrel 35 extends into the wave. guide tubing 19 and supports its internal walls during the bending operation.

Forming die The forming die 13 has therein a circular groove 36 (Fig. 2) which has an angular cross-section that is formed with the angle required for the desired degree of bend for the tube 19. In the case of a twisted bend the groove 36 gradually changes angle, i. e., its cross-section rotates about the axial center of the tubing to be bent according to the degree of twist desired. It is essential that this groove be formed in such a way that the center line of a tube nested within it lies in a true circular arc equidistant from the center of rotation of the forming die- 13. The circular guides 25 in the upper and lower surfaces of the forming die have their centers of curvature coincident with the axis of rotation of the forming die 13;

Wiper die The longitudinal cylindrical sink 27 (Fig. 3) in the first pillow block 26 has nested therein the wiper die 29, a pair of faces 37 which are shaped complementary to the wave guide tubing 19 and are in engagement there with. The wiper die 29 cooperates with the forming die 13 to supportthe walls of the wave guide tubing 19 that are. under compression during bending. The wiper die 29 is. prevented from moving rectilinearly as the tubing 3 19 is advanced by the forming die 13 by a shoulder or key portion 66 formed on the die 29. As the forming die 13 is rotated about its vertical axis to initiate bending of the wave guide tubing .19 the trailing portion of the wave guide tubing 19 rotates about its longitudinal axis due to the twist imparted to the wave guide tubing by the circular groove 36 in the forming die 13. The wiper die 29 may rotate with the rotation of the trailing portion of the tubing 19 as the shoulder or key portion 66 may move in a substantially semi-circular groove 67 in the pillow block 26. The wave guide tubing 19 except for the clamped end 38 is free to rotate about its longitudinal axis because the wiper die 29 is rotatably nested in the pillow block 26. However, since the wiper die 29 remains in engagement with the tubing 19 while it is being twisted, the wiper die supports the critical portions of the tubing 19 during the entire bending operation.

Pressure die Bifurcations 42 in the yoke 21 (Figs. 2 and 3) straddle the forming die 13, and the pins 24 extend through-these bifurcations into the circular guides 25 in the upper and lower surfaces of the forming die 13 thereby preventing relative horizontal rectilinear motion between the forming die 13 and the yoke 21, but allowing the forming die to rotate relative to the yoke.

The second pillow block 30 is slidably positioned between the bifurcations 42 of the yoke 21 and the longitudinal cylindrical sink 32 in the second pillow block has rotatably nested therein the pressure die 34. An angular groove 43 in the pressure die 34 is shaped complementary to the wave guide tubing 19 and when set screws 31 are threaded into the yoke 21 the sides of the angular groove 43 contact walls 45 and 46 of the wave guide tubingto prevent the left or trailing portion of the wave guide tubing 19 from rotating about the axis of rotation of the forming die as it is turned by the sprocket and chain drive 16 (Fig. 8). In order to gain support beyond the tangent line of the bend, the pressure die 34 extends beyond the tangent line by approximately three-fourths of an inch, thus providing support at the start of the bending operation. The pressure die 34 is prevented from moving rectilinearly as the tubing 19 is advanced by the forming die 13 because of shoulders 68 on the pressure die 34 which extend on opposite sides of the pillow block 30. The pillow block 30 is in turn held against movement by the studs or screws 31 engaging the surface of the pillow block 30. In the alternative, the

pillow block 30 may be prevented from moving by end plates such as are shown as 63 in Figs. 6 and 7, or by being provided with apertures into which the screws 31 may extend. A shim 49 is mounted in a slot 50 in the face of the pressure die 34; the slot 50 being curved at its end as at 59, Figs. 12 and 13, in such a way that if a shim of uniform thickness lies against the curve 59, a curved support starting at the tangent line of the bend will be afforded the expanding tube wall. A side of the shim 49 is curved to fit the pressure die slot 50 and the side adjacent the Wave guide tubing 19 is flat.

The shim 49 moves forward with the tubing as bending progresses and thus presents its full thickness between the curved pressure die 34 and the wave guide tubing 19 thereby providing continuous support throughout the bending process. The shim 49 is also provided at its one end with a curved surface to correspond with the curved surface 59 of the slot 50, as seen in Fig. 13. The shim 49 should be of such length that after thebending operation is completed with the forward end of the shim as shown in Fig. 11 a portion of the shim will still remain within the slot 50 in the pressure die 34, thereby insuring support during the entire operation.

'Figs. 6-8 illustrate a modification of the bending apparatus. The circular guide 25 and pins 24 for connecting the yoke 21 and the forming die 13 are replaced by a protruding ring portion 52 of the yoke 21' which is 4 mounted on shaft 14 and is held thereon by lock nut 53. Further, the yoke 21 is not a unitary bifurcated member, but instead is formed of top and bottom plates 61, a front plate 62 and and supporting and reinforcing members 63.

The mandrel 35 is of a universal twisting type such as is disclosed in applicants co-pending application, Serial Number 313,718, filed October 8, 1952, and is inserted in the tube before the bending operation begins, thus supporting the internal walls of the tube 19 during the bending operation.

In forming'a desired diagonal twisted bend in a wave guide tube, the wave guide tube 19 is started on the mandrel 35 and is then placed against the forming die 13 and the wiper die 29. The clamping die 17 is then moved forward by the piston 20 to rigidly clamp the wave guide tube 19 to the forming die 13. The set screws 31 are tightened to force the pressure die 34 into engagement with the tube 19, the pressure die thereby preventing the left end of the tube 19 from moving outward during the bending operation. The shim 49 should be inserted in the slot 50 in the pressure die 34 before the set screws 31 are tightened, and positioned with its forward curved end so as to be in engagement with the tube 19 when the screws 31 are tightened. In the alternative, the shim may be inserted to its proper distance before the tube 19 and mandrel 35 are positioned in place. The mandrel 35 is then moved to the right into the tube 19 (Fig. 5). After the mandrel is correctly positioned within the tube 19, the forming die 13, the clamping die 17, and their associated supporting structures are rotated counterclockwise (Fig. 5) to the position shown in Fig. 11 by means of the shaft 14 which is driven by the sprocket 15 and the chain drive 16. As the forming die 13 rotates, the tube 19 is drawn over the mandrel 35 and in wiping engagement with the wiper die 29 and thence around the forming die 13. As mentioned previously, during the rotation of the forming die 13 and the forward movement of the tubing 19 the wiper die 29 and pressure die 34 are free to rotate in the pillow blocks 26 and 30.but are prevented from moving rectilinearly.

Upon completion of the bending operation, the mandrel 35 is withdrawn from the bent tube 19; the clamping die 17'and the pressure die 34 are retracted, the shim 49 is replaced in the slot 50 to its unoperated position and the bent tube 19 is then removed from the apparatus by the operator.

Although i the invention has been described with reference to particular embodiments, it is to be understood that various modifications may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. An apparatus for forming a diagonal twisted bend in wave guide tubing comprising a rotatable forming die, means for clamping one end of the wave guide tubing to said forming die during bending, a wiper die positioned adjacent said forming die for supporting the portions of the wave guide tubing that are under compression during bending, said wiper die being immovable rectilinearly during the forming operation but rotatable along the longitudinal axis of the wave guide tubing, and a pressure die positioned adjacent said forming die and opposite said wiper die and immovable rectilinearly during the forming operation but rotatable around the longitudinal axis of said wave guide tubing to confine the motion thereof .to rectilinear motion along and rotational motion around its longitudinal axis. a 1

2. An apparatus for forming a diagonal twisted bend in wave guide tubing comprising a base, a forming die rotatably mounted on said base, 'a clamping die for clamping one end of said wave guide tubing to said forming die during bending, a yoke straddling said formdie to support the portions of said wave guide tubing that are under compression during bending, means for rotatably attaching said wiper die to said yoke so that the wiper die is rotatable along the longitudinal axis ofthe wave guide tubing, a pressure die positioned within said yoke for preventing rotation of the other end of said wave guide tubing around the axis of rotation of said forming die, and means for mounting said pressure die within said yoke so that the pressure die is rotatable around the longitudinal axis of said wave guide tubing.

3. A bending apparatus for cooperating with a rotatable forming die which has one end of a wave guide tubing secured thereto by a clamping die during bending, comprising a bifurcated yoke straddling said forming die, means rotatably attaching said forming die to said yoke, a pillow block positioned within said yoke and having a longitudinal cylindrical sink in one face, a pressure die rotatably nested in said longitudinal cylindrical sink for engaging the other end of said wave guide tubing to prevent its turning about the axis of rotation of said forming die, said pressure die having a curved slot in its wave guide engaging face, and a shim slidably positioned in said curved slot for engaging and supporting a Wall of said wave guide tubing.

4. An apparatus for forming a diagonal twisted bend in wave guide tubing comprising a bifurcated yoke, a forming die rotatably attached to said bifurcations of the yoke, means for clamping one end of the wave guide tubing to the forming die during the bending operation, a wiper die positioned adjacent said forming die to support the walls of said wave guide tubing that are in compression during bending, means for rotatably attaching said wiper die to said yoke so that the wiper die is rotatable along the longitudinal axis of the wave guide tubing, a pressure die for preventing rotation of the other end or said wave guide tubing around theaxis of rotation of the forming die, and means for rotatably attaching said pressure die to said yoke so that said pressure die is rotatable around the longitudinal axis of said wave guide tubing.

5. An apparatus for forming a diagonal twisted bend in wave guide tubing comprising a forming die having an angular cross-sectional groove in its wave guide engaging face, the angle of said cross-section being formed with the degree of twist to be imparted to the wave guide tubing to be bent, means for clamping one end. of the wave guide tubing to said forming die during the bending operation, wiping means immovable rectilinearly during the forming operation to rotatably support the portions of said wave guide tubing that are adjacent said forming die so that said wave guide tubing is rotatable around its longitudinal axis, and means opposite said wiping means immovable rectilinearly during the forming operation for engaging said wave guide tubing so that it is rotatable only about its longitudinal axis but is rectilinearly movable along said longitudinal axis.

6. An apparatus for forming a diagonal twisted bend in a wave guide tube comprising a bifurcated yoke, a rotatable forming die positioned within the bifurcations of said yoke and having circular guides in its faces adjacent said bifurcations, means for clamping one end of a wave guide tube to said rotatable forming die during bending, means securing the bifurcations of said yoke to said circular guides so that the forming die is rotatable relative to said yoke and is rectilinearly immovable relative thereto, a pressure die positioned within the bifurcations of said yoke and in engagment with the walls of the wave guide tube opposite said forming die, and means for rotatably attaching said pressure die to said yoke so that the pressure die prevents rotation of the other end of said wave guide tubing around the axis of rotation of said forming die and so that the wave guide tube is rotatable about, and rectilinearly movable along, its longitudinal axis.

7. An apparatus for forming a diagonal twisted bend in a rectangular wave guide tube comprising a rotatable forming die having a circular track in each of its u per and lower surfaces, the central axis of said tracks being coincident with the center of rotation of said rotatable forming die, means for clamping one end of said wave guide tube to said rotatable forming die duringbending, said rotatable forming die having an angular crosssectional groove in its wave guide engaging face, said angular cross-sectional groove varying in its rotative. position relative to the longitudinal axis of the wave guide tubing so that the wave guide. tube is twisted as it. is drawn and bent by said forming die, and means for preventing rotation of the. other end of said wave guide tube about the axis of rotation of said forming die but allowing rotation of said wave guide tube around its longitudinal axis, said means cooperating with said circular tracks to prevent relative recilinear motionfbetween said forming die and said means during bending.

8. An apparatus for forming a diagonal twisted bend in a wave guide tube comprising a bifurcated yoke, a

rotatable forming die positioned within the bifurcations of said yoke, means rotatably attaching said rotatable forming die to said yoke, means for clamping one end of said wave guide tube to the forming die during the bending operation, a pillow block positioned within said yoke and having a longitudinal cylindrical sink therein, a rotatable pressure die nested in said longitudinal cylindrical sink, and having an angular groove in one face that is adapted to engage said wave guide tube so that said wave guide tube is rotatable around, and rectilinearly movable along its longitudinal axis, and actuating means for moving said pressure die into engagement with the wave guide tube so that the other end of said wave guide tube is not rotatable about the axis of rotation of said rotatable forming die.

9. An apparatus for forming a diagonal twisted. bend in rectangular wave guide tubing comprising a bifurcated yoke, a rotatable forming die having a circular guide 'in each of its upper and lower surfaces and positioned within said bifurcated yoke, the central axis of said guides-being coincident with the center of rotation of said rotatable forming die, means for clamping one end of said wave guide tubing to said rotatable forming die during the bending operation, means slidably securing said hifurcations of said yoke in said circular guides-so that said forming die. is rotatable relative to said yoke, said rotatable forming die having an angular cross-sectional groove in its Wave guide engaging face, the angular cross-section of said groove varying in its rotative position relative to the longitudinal axis of said wave guide tubing so that the wave guide tubing is twisted as it is drawn and bent by said forming die, a pillow block slidably mounted at the base of the bifurcations of said yoke and having a longitudinal cylindrical sink in a face thereof, a pressure die rotatably nested in said longitudinal cylindrical sink and having an angular groove in its Wave guide engaging face for supporting the walls of said wave guide tubing opposite said forming die, said pressure die being rotatable about the longitudinal axis of said wave guide tubing so that the tubing is free to rotate around its longitudinal axis as it is drawn and bent by said forming die, and means to move said pressure die into and out of engagement with said wave guide tubing.

10. An apparatus for forming a diagonal bend in a wave guide tube comprising a bifurcated yoke, a rotatable forrning die having circular tracks in its faces, the central axis of said circular tracks being coincident with the center of rotation of said rotatable forming die, means for clamping one end of said wave guide tube to said rotatable forming die during the bending operation, means attached to said bifurcations of said yoke and extending into said circular tracks so that said forming die is rotatable relative to said yoke, said rotatable forming die having an angular cross-sectional groove in its wave guide engaging face, the angular cross-section of said groove variable in its rotative position relative to the longitudinal axis of said wave guide tube, so that the Wave guide tube is twisted as it is drawn and bent, a first pillow block secured to the bifurcations of said yoke and having able towards and away from the wave guide tube, said second pillow block having a longitudinal cylindrical sink in the face thereof, a cylindrical pressure die rotatably :nested in said longitudinal cylindrical sink. and having an angular groove in its wave guide engaging face for engaging the walls of said wave guide tube that are opposite said forming die, said pressure die being rotatable around the longitudinal axis of said wave guide tube 'so that the tube is rotatable about said longitudinal axis 'as it is drawn and bent by said forming die, and means to move said second pillow block toward and away from said wave guide tube so that the pressure die nested therein moves into and out of engagement with the walls of said wave guide tube.

11. An apparatus for bending a wave guide tube comprising a base, a forming die rotatably mounted on said base, a clamping die for clamping an end of the wave guide tube to said forming die, a yoke positioned on said base adjacent said forming die, a first pillow block at tached to said yoke and having a cylindrical sink therein, a wiper die nested in said cylindrical sink and rotatable therein, said wiper die being adjacent said forming die and cooperating therewith to support the external walls of the waveguide tube that are in compression during bending, a second pillow block attached to said yoke and having a second cylindrical sink therein, a pressure die rotatably nested in said second cylindrical sink and cooperating with said forming die and said wiper die to support said wave guide tube during bending, and means for forcing the pressure die into contact with said wave guide tube.

'12. An apparatus for forming a diagonal twisted bend in a wave guide tube comprising a base; a forming die rotatably mounted on said base and having circular tracks in its upper and lower surfaces, the vertical axis of said tracks being coincident with the axis of rotation of ,the forming die, said forming die having a groove in'its wave guide engaging face that is complementary to the wave guide tube and whose angular cross-section is vari:

able in its orientation with respect to the longitudinal axis of said. wave guide tube, means for rotating'said forming die to bend the wave guide tube, a clamping die for holding one end of the wave guide tube in engagement with said forming die during bending, means formoving said clamping die into and out of engagement with said wave guide tube, a bifurcated yoke, means attaching the bifurcations of said yoke to the circular tracks in said forming die so that said yoke is prevented from moving rectilinearly relative to said forming die and so that said forming die may rotate relative to said yoke, a first pillow block attached to the bifurcations of said yoke and having a longitudinal cylindrical sink therein, a wiping die shaped complementaly to said cylindrical sink and rotatably nested therein, said wiping die being positioned adjacent said forming die and in engagement with 7 forming die, said pressure die being rotatable about the longitudinal axis of said wave guide tube so that the tube is free to rotate around said longitudinal axis as it is drawn and bent by said forming die, and means to move said pressure die into and out of engagement with said wave guide tube.

References Cited in the file of this patent UNlTED STATES PATENTS 757,593 Atwood Apr. 19, 1904 1,261,191 Vallone Apr. 2, 1918 1,982,164 loener Nov. 27, 1934 2,255,867 Wisckol Sept. 16, 1941 FOREIGN PATENTS 299 Great Britain Ian. 6, 1892 

